Preparation of Hydrophobic Silica Particles for Superhydrophobic Modified Waterborne Polyurethane Resin
In order to prepare the modified waterborne polyurethane resin with stable superhydrophobic properties,inspired by the"Lotus Effect"and based on the alkaline hydrolysis reaction of dodecyltriethoxysilane(DTES),a long-chain alkane structure with low surface energy was introduced on the surface of SiO2 particles through the grafting reaction of hydroxyl groups on the surface.Thus,microcapsule coated silica particles with hydrophobic effect were prepared.To determine the preparation method and law of hydrophobic modified particles,the structures of the particles were characterized by infrared spectroscopy(FT-IR),X-ray diffraction(XRD),scanning electron microscopy(SEM)and other testing methods.Then aqueous polyurethane coatings with superhydrophobic properties were prepared by physical blending of self-made modified SiO2 particles and waterborne polyurethane resin(WPU).Using differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA)to characterize the blending properties and heat resistance of the coatings,using scanning electron microscopy(SEM)and atomic force test(AFM)to quantitatively analyze the characteristics and surface morphology of the coatings,and using water absorption capacity(WAC)to characterize super hydrophobic properties and surface energy of the waterborne coatings.The results show that the self-made hydrophobic particles migrated to the surface of the epoxy resin and formed a stably rough surface structure through chemical action and physical entangling.Combined with the low surface energy modification of the long chain alkane,the resin is superhydrophobic and the contact angle reaches 158°.Moreover,compared with pure WPU,the root mean square roughness(Rq)of the product coating increases from 7.82 nm to 101 nm,and the average roughness(Ra)increases from 6.24 nm to 77.9 nm,which greatly improves the surface roughness.By combining the water-based resin preparation with superhydrophobic properties,the water-based polyurethane with green environmental protection and self-cleaning effect was prepared.The special resin coating's surface maintains the stability and durability of the structure in harsh environment,and shows excellent wear and chemical corrosion resistance.
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